Rackspace servers.Create fails without a DiskConfig

[smashwilson]

Whoops:

s, err := servers.Create(d.Client, servers.CreateOpts{
    Name:      name,
    ImageRef:  d.ImageID,
    FlavorRef: d.FlavorID,
    KeyPair:   d.KeyPairName,
}).Extract()

[2014-10-24T08:20:43.091971990-04:00] [fatal] log.go:64 Expected HTTP response code [202] when accessing URL(https://iad.servers.api.rackspacecloud.com/v2/864477/servers); got 400 instead with the following body:
{"badRequest": {"message": "OS-DCF:diskConfig must be either 'MANUAL' or 'AUTO'.", "code": 400}}

I'm glad I'm testing these things 😉

[smashwilson]

(This is probably a problem with the DiskConfig extension.)

[smashwilson]

@jrperritt is taking care of this in #259. ✨

[smashwilson]

Confirmed fixed.